Search for bacterial α1,2-fucosyltransferases for whole-cell biosynthesis of 2′-fucosyllactose in recombinant Escherichia coli

Abstract

2′-Fucosyllactose (2′-FL) is the most abundant human milk oligosaccharide and is important for infant nutrition and health. Because 2′-FL has potential as a functional ingredient in advanced infant formula and as a prebiotic in various foods, a cost-effective method for 2′-FL production is desirable. α1,2-Fucosyltransferase (α1,2-FT) is one of the key enzymes enabling the microbial biosynthesis of this complex sugar. However, the α1,2-FTs reported so far for the whole-cell biosynthesis of 2′-FL originate from pathogens, posing a potential hurdle for approval as a food production method depending on countries. In this study, 10 α1,2-FT genes from bacteria of biosafety level one were identified, and the main features of the deduced amino acid sequences were characterized. Four codon-optimized α1,2-FT genes were synthesized and introduced into Escherichia coli ΔL M15 strain containing the plasmid pBCGW encoding guanosine 5′-diphosphate-l-fucose biosynthetic enzymes. Among the four genes, 2′-FL was produced only by the α1,2-FT from Thermosynechococcus elongatus (Te2FT). Bifidobacterium thermacidophilum α1,2-FT (Bt2FT) showed high expression but was not active in E. coli ΔL M15. The other two α1,2-FTs were not expressed to a detectable level. During batch flask fermentation of Te2FT-expressing E. coli ΔL M15 cells, 0.49 g/L 2′-FL was obtained after 72 h of induction. This is comparable to the values previously reported for α1,2-FTs from Helicobacter pylori and Bacteroides fragilis.